Photometric optical sensors are among the most commonly used measurement principles for online analyzers.
These methods are based on measuring the interaction of light with the sample and the measurement principle is usually based on Beer-Lambert Law which states about a linear relationship between absorbance and concentration of absorbing species.
According to the law:
They are often employed for their simplicity and rapid response.
The majority of commercially available photometric sensors fall into main three categories.
- Colorimetric
- UV Absorption and
- UV Visible absorption
Optical sensors, such as non-destructive sensors arrays, have the advantage over ISE (Ion Selective electrodes) for water quality monitoring as in these analyzers gross fouling and potential problems or contamination can be detected by color changes in the sample.